Pneumatic detector switch



Aug 13, l940. o. K. NoRMANN PNEUMATIC DETECTOR SWITCH Filed Nov. '7,1959 gwoon/bw Olm/KMrmann www Patented ug. 13, 1940 PATENT OFFICEPNEUMATIC DETECTOR SWTCH Olav K. Normanni, Arlington, `ifa.; dedicatedto the free use of the People in the territory of the United StatesApplication November 7, 1939, Seriai No. 303,287

6 Claims.

(Cl. 20G-83) (Granted under the act of March 3, 1883, as amended April30, 1928; 370 0. G. 757) This application is made under the act of March3, 1883, as amended by the act of April 30, 1928, and the inventionherein described and claimed, if patented, may be manufactured and usedby or for the Government of the United States of America forgovernmental purposes without the payment to me of any royalty there- Ihereby dedicate the invention herein described to the free use of thePeople in the terri- Atory of the United States to take effect on thegranting of a patent to me.

This invention relates to pneumatic detector switches and is moreparticularly concerned with a switch which may be used in conjunctionwith a pneumatic impulse traffic tube stretched across a highway forexcitation by the wheels of Vehicles moving thereover and in conjunctionwith a counting mechanism which records the number of contacts made bythe switch.

One of the objects of this invention is to provide a switch of the typementioned which in operation does not depend upon the elasticity of anyparticular material, such as is required in the types of switches usingflat diaphragms.

Another object of this invention is the provision of means for adjustingthe operating characteristics of the device, especially its sensitivity.

Another object of this invention is the provision of an instrument ofthe type mentioned which is hermetically sealed, which may be easilydissembled and repaired, and which occupies a very small space.

The following description, considered together with the accompanyingdrawing, will disclose this invention more fully, its construction,arrangements, and combinations of parts, and further objects andadvantages thereof will be apparent.

The accompanying drawing illustrates a longitudinal partial section of adevice embodying the features of this invention in one of its preferredforms.

Referring with more particularity to the drawing in which like numeralsdesignate like parts,

the numeral I designates the main housing of the instrument fabricatedof an electrical conducting material, at one end of which is secured anipple 2 by means of a reducer 3. The nipple 2 extends outward and isadapted to receive a trame impulse tube 4, which is made of a resilientmaterial, such as rubber. This tube is an element well known in the artand is employed by stretching it across the highway where moving trafcruns over it and sends an air impulse through it. If desired, this tubemay be open at its free end, or otherwise perforated, in accordance withrecently developed practice in this art, to prevent surging. The otherend of the nipple 2 extends within the reducer 3, over which is attachedan inflatable sac 5 of rubber or any other 5 suitable material such asthat commonly used as ink reservoirs in fountain pens.

On one side of the sac 5 there is disposed a strip of resilientlyyieldable material 5, such as spring steel, the forward end of which isfixed 10 to the housing I by any suitable means, such as a lug 'l and ascrew 8. The other end of the strip t is free and abuts a set screw 9disposed through the wall of the housing, substantially as shown. Bythese means, the displacement 15 of the strip B with respect to thehousing I may be adjusted. A pair of lips It are disposed, one on eachside of the strip 5, to hold the sac 5 in place laterally. On theopposite side of the sac 5, there is disposed another resilientlyyieldable 20 strip of material i I, preferably of spring steel. Thisstrip of material l I is provided with a U-turn at the forward endforming a short arm I2 adjacent to the housing, the lon-g arm I3 beingadjacent to the sac 5, and it comprises one of the 25 contact arms ofthe switch. The strip is secured to the wall of the housing by means ofthis short arm I2 and a screw Ill engaging pressure plate I5. Also thisstrip II is insulated from the housing I by any suitable means, such 30as insulating blocks I6, inserted between it and the housing andinsulating material Il and I8 introduced between the screw I4 and thehousing. The long arm I3 of the strip II has a crimped portion I9 whichpresses against the sac 5, sub- 35` stantially as shown.

Opposite the long arm i3 of the strip II is disposed another strip orarm 25, also preferably of spring steel, comprising the other contactarm of the switch, and it is fixed at one end to the 40 housing I, theother end being free and terminating at substantially the same pointalong the axis of the instrument as the arm I3. At the free ends of thearms i3 and 20 are secured electrical contact points 2i and 22. Thedistance 45 between these two contact points is made adjustable by meansof an adjustable abutment screw 23 disposed through the housing I andcontacting the strip 20, substantially as illustrated.

The rearward end of the housing I is provided 50 with a cap 24, inthreaded engagement, thereby completely enclosing the interior of theswitch. The cap 24 is provided with an eye 25 which may be useful insecuring the device in selected positions while in operation, such as toa post, tree, 55

and so forth. A binding post 26 is secured to cap 2&3 as a terminal forone of the electrical leads 2l, 27 of the recording mechanism circuit(not shown). The other terminal is provided by the screw I4 which isiitted with a floating nut 29.

The operation of this invention is as follows: The air impulse generatedby a vehicle passing over the tube stretched across a highway causes thesac 5 to expand at points Where it is compressed by the arm l2,particularly at the point where thecrimp I9 contacts the sac. 'Ihiscauses the arm i3 to move toward the arm 20, thereby causing the contactpoints 2l and 22 to touch, which closes the electrical circuit betweenthe wires 2l, 2l attached to the terminals 26 and lli. When the impulserecedes, the contact between the points 2l and 22 is broken due to therelease of pressure in the sac 5 and the resilient action of the stripH.

By means of the adjusting abutment screw 9, the sensitivity of theinstrument may be regulated since this adjustment permits controllingthe location of the sac 5 with respect to the arm i3. Also the distancebetween the contact points 2l and 22 may be adjusted by means of the setscrew 23.

Having thus. described my invention, I claim:

i. A pneumatic detector switch comprising a housing, an inflatable sacwithin said housing communicable with a pneumatic impulse tube,electrical contact elements in juxtaposition to said sac and responsiveto inflations thereof, means for adjusting the responsive relationbetween said sac and said contact elements, and means for adjusting therelation between said contact elements independently of said responsiverelation.

2. A pneumatic detector switch comprising a housing, an inatable sacwithin said housing communicable with a pneumatic traflc impulse tube, apair of resiliently yieldable arms secured within said housing, saidarms being electrically insulated from each other, one of said armsbeing biased against said sac and the other being adjustably fixed tosaid housing, a pair of electrical contact points secured to said arms,one contact point for each arm, and means for adjusting the biasedrelation between said sac and its corresponding yieldable arm.

3. A pneumatic detector switch comprising a housing; an iniiatable sacwithin said housing communicable with a pneumatic traic impulse tube; apair of resiliently yieldable arms secured Within said housing, saidarms being electrically insulated from each other, one of said armsbeing biased against said sac and having a portion thereof projectingagainst said sac, the other arm being adjustably fixed to said housing;a pair of electrical contact points secured to said arms, one contactpoint for each arm; and means for adjusting the biased relation betweensaid sac and its corresponding yieldable arm.

4. An article of manufacture comprising a tubular housing having aremovable cap at its rearward end and a nipple conduit removably securedat its forward end, a resilientlyyieldable arm within said housinghaving one end secured at the forward end thereof, an adjustableabutment for the other end of said arm, an inflatable longitudinal sacresting on said yieldable arm communicating with said conduit, anelectrical contact arm biased against said sac, another electricalcontact arm opposite said first-mentioned contact arm and electricallyinsulated therefrom, means for adjusting the relation between saidcontact arms, and means for connecting said arms in an electricalcircuit.

5. An article of manufacture comprising a tubular housing having aremovable cap at its rearward end and a nipple conduit removably securedat its forward end, a resiliently yieldable arm within said housinghaving one end secured at the forward end thereof, an adjustableabutment for the other end of said arm, an iniiatable longitudinal sacresting on said yieldable arm communicating with said conduit, lateralabutments on said arm to hold said sac in alignment, an electricalcontact arm biased against said sac, another electrical contact armopposite said first-mentioned contact arm and electrically insulatedtherefrom, means for adjusting the relation between said contact arms,and means for connecting said arms in an electrical circuit.

6. An article of manufacture comprising a tubular housing having aremovable cap at its f rearward end and a nipple conduit removablysecured at its forward end, a resiliently yieldable arm within saidhousing having one end secured at the forward end thereof, an adjustableabutment for the other end of said arm, an inflatable longitudinal sacresting on said yieldable arm communicating with said conduit, lateralabutments on said arm to hold said sac in alignment, a crimpedelectrical contact arm biased against said sac, another electricalcontact arm opposite said first-mentioned contact arm and electricallyinsulated therefrom, means for adjusting the relation between saidcontact arms, and means for connecting said arms in an electricaleircuit.

OLAV K. NORMANN.

